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The extreme cost of heating moisture in construction

What’s the difference between a 3kW heater and a dehumidifier on a six month hire? About £2,395 in electricity consumption – seriously!

It’s for this reason that I wanted to share a blog to talk about the differences between heating and dehumidifying, as we’re finding many are still heating construction spaces unnecessarily.

How does heat affect moisture?

Most notably, heat simply manipulates the air’s ability to retain moisture. So essentially a heater doesn’t reduce moisture content, it just displaces it. That’s not to say there’s no place for them in the drying out of a building. For example in the cooler months, when vapour pressure is low, heaters of course aid with comfort levels. Heat can also be required for the installation of certain products but positive pressure is required for correct ventilation. However, it is necessary to pay attention to the source of the heat – if it contains combustion gases then it is deemed unsafe to recirculate.

Problems also lie where people think it’s ok to vigorously heat space to dry out moisture. This is wrong as it only expands the atmosphere, drawing the moisture from the materials into the air. Once that heat is removed, it will return from the air back into the building’s fabric, therefore exacerbating the issue and wasting loads of energy!

How does dehumidification affect moisture?

Essentially, dehumidification removes water vapours from the air completely by drawing air from the environment over a coil and reducing to a very low temperature via a refrigeration system. This essentially cools the air below the dew point temperature so that it condenses and drains away. You may hear of desiccant dehumidifiers – these perform well at low temperatures and in cold, damp weather, making them ideal for outdoor use, as well as indoor use. With airflow capacities up to 7000 m3/hr, Aggreko’s industrial dehumidifiers are capable of drying out very large areas.

Cost implications

To put the above into perspective, I have shown below an estimated difference in price between a 3kW heater and a dehumidifier – it’s essentially 73% cheaper to run a dehumidifier:

  • 1 week hire = £99.82
  • 1 month hire = £399.28
  • 6 month hire = £2,395.68

At Aggreko, we believe temperature and moisture control should be a gradual process on construction sites, with each stage of the process being independently assessed and optimised.

If this is a topic you'd like to find out more about, you can download my latest guide, "The true cost of humidity on site."